/**
 * Provides a method to encode any string into a URL-safe
 * form.
 * Non-ASCII characters are first encoded as sequences of
 * two or three bytes, using the UTF-8 algorithm, before being
 * encoded as %HH escapes.
 *
 * Created: 17 April 1997
 * Author: Bert Bos <bert@w3.org>
 *
 * URLUTF8Encoder: http://www.w3.org/International/URLUTF8Encoder.java
 *
 * Copyright �0�8 1997 World Wide Web Consortium, (Massachusetts
 * Institute of Technology, European Research Consortium for
 * Informatics and Mathematics, Keio University). All Rights Reserved.
 * This work is distributed under the W3C�0�3 Software License [1] in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE.
 *
 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
 */
package com.letianpai.common.tool;
/**
 * Created by IntelliJ IDEA.
 * User: Chris.F
 * Date: 2009-2-24
 * Time: 10:32:52
 */
public final class URLUtil {

    private final static String[] hex = {
            "%00", "%01", "%02", "%03", "%04", "%05", "%06", "%07",
            "%08", "%09", "%0a", "%0b", "%0c", "%0d", "%0e", "%0f",
            "%10", "%11", "%12", "%13", "%14", "%15", "%16", "%17",
            "%18", "%19", "%1a", "%1b", "%1c", "%1d", "%1e", "%1f",
            "%20", "%21", "%22", "%23", "%24", "%25", "%26", "%27",
            "%28", "%29", "%2a", "%2b", "%2c", "%2d", "%2e", "%2f",
            "%30", "%31", "%32", "%33", "%34", "%35", "%36", "%37",
            "%38", "%39", "%3a", "%3b", "%3c", "%3d", "%3e", "%3f",
            "%40", "%41", "%42", "%43", "%44", "%45", "%46", "%47",
            "%48", "%49", "%4a", "%4b", "%4c", "%4d", "%4e", "%4f",
            "%50", "%51", "%52", "%53", "%54", "%55", "%56", "%57",
            "%58", "%59", "%5a", "%5b", "%5c", "%5d", "%5e", "%5f",
            "%60", "%61", "%62", "%63", "%64", "%65", "%66", "%67",
            "%68", "%69", "%6a", "%6b", "%6c", "%6d", "%6e", "%6f",
            "%70", "%71", "%72", "%73", "%74", "%75", "%76", "%77",
            "%78", "%79", "%7a", "%7b", "%7c", "%7d", "%7e", "%7f",
            "%80", "%81", "%82", "%83", "%84", "%85", "%86", "%87",
            "%88", "%89", "%8a", "%8b", "%8c", "%8d", "%8e", "%8f",
            "%90", "%91", "%92", "%93", "%94", "%95", "%96", "%97",
            "%98", "%99", "%9a", "%9b", "%9c", "%9d", "%9e", "%9f",
            "%a0", "%a1", "%a2", "%a3", "%a4", "%a5", "%a6", "%a7",
            "%a8", "%a9", "%aa", "%ab", "%ac", "%ad", "%ae", "%af",
            "%b0", "%b1", "%b2", "%b3", "%b4", "%b5", "%b6", "%b7",
            "%b8", "%b9", "%ba", "%bb", "%bc", "%bd", "%be", "%bf",
            "%c0", "%c1", "%c2", "%c3", "%c4", "%c5", "%c6", "%c7",
            "%c8", "%c9", "%ca", "%cb", "%cc", "%cd", "%ce", "%cf",
            "%d0", "%d1", "%d2", "%d3", "%d4", "%d5", "%d6", "%d7",
            "%d8", "%d9", "%da", "%db", "%dc", "%dd", "%de", "%df",
            "%e0", "%e1", "%e2", "%e3", "%e4", "%e5", "%e6", "%e7",
            "%e8", "%e9", "%ea", "%eb", "%ec", "%ed", "%ee", "%ef",
            "%f0", "%f1", "%f2", "%f3", "%f4", "%f5", "%f6", "%f7",
            "%f8", "%f9", "%fa", "%fb", "%fc", "%fd", "%fe", "%ff"
    };

    private static final char[] reserved = {
            '-', '_', '.', '!', '~', '*', '\'', '(',
            ')', '/', '&', '?', '#', '%', ':'
    };

    private static boolean isReserved(char ch) {
        for (char item : reserved) {
            if (ch == item) return true;
        }
        return false;
    }


    /**
     * Encode a string to the "x-www-form-urlencoded" form, enhanced
     * with the UTF-8-in-URL proposal. This is what happens:
     * <p/>
     * <ul>
     * <li><p>The ASCII characters 'a' through 'z', 'A' through 'Z',
     * and '0' through '9' remain the same. </p>
     * <p/>
     * <li><p>The unreserved characters - _ . ! ~ * ' ( ) remain the same. </p>
     * <p/>
     * <li><p>The space character ' ' is converted into a plus sign '+'. </p>
     * <p/>
     * <li><p>All other ASCII characters are converted into the
     * 3-character string "%xy", where xy is
     * the two-digit hexadecimal representation of the character
     * code </p>
     * <p/>
     * <li><p>All non-ASCII characters are encoded in two steps: first
     * to a sequence of 2 or 3 bytes, using the UTF-8 algorithm;
     * secondly each of these bytes is encoded as "%xx". </p>
     * </ul>
     *
     * @param s The string to be encoded
     * @return The encoded string
     */
    private static String encode(String s) {
        StringBuffer sbuf = new StringBuffer();
        int len = s.length();
        for (int i = 0; i < len; i++) {
            int ch = s.charAt(i);
            if ('A' <= ch && ch <= 'Z') {        // 'A'..'Z'
                sbuf.append((char) ch);
            } else if ('a' <= ch && ch <= 'z') {    // 'a'..'z'
                sbuf.append((char) ch);
            } else if ('0' <= ch && ch <= '9') {    // '0'..'9'
                sbuf.append((char) ch);
            } else if (isReserved((char) ch)) {    // unreserved
                sbuf.append((char) ch);
//            } else if (ch == ' ') {            // space
//                sbuf.append('+');
            } else if (ch <= 0x007f) {        // other ASCII
                sbuf.append(hex[ch]);
            } else if (ch <= 0x07FF) {        // non-ASCII <= 0x7FF
                sbuf.append(hex[0xc0 | (ch >> 6)]);
                sbuf.append(hex[0x80 | (ch & 0x3F)]);
            } else {                    // 0x7FF < ch <= 0xFFFF
                sbuf.append(hex[0xe0 | (ch >> 12)]);
                sbuf.append(hex[0x80 | ((ch >> 6) & 0x3F)]);
                sbuf.append(hex[0x80 | (ch & 0x3F)]);
            }
        }
        return sbuf.toString();
    }

    public static String decode(String s) {
        StringBuffer sbuf = new StringBuffer();
        int l = s.length();
        int ch = -1;
        int b, sumb = 0;
        for (int i = 0, more = -1; i < l; i++) {
            /* Get next byte b from URL segment s */
            switch (ch = s.charAt(i)) {
                case '%':
                    ch = s.charAt(++i);
                    int hb = (Character.isDigit((char) ch)
                            ? ch - '0'
                            : 10 + Character.toLowerCase((char) ch) - 'a') & 0xF;
                    ch = s.charAt(++i);
                    int lb = (Character.isDigit((char) ch)
                            ? ch - '0'
                            : 10 + Character.toLowerCase((char) ch) - 'a') & 0xF;
                    b = (hb << 4) | lb;
                    break;
                case '+':
                    b = ' ';
                    break;
                default:
                    b = ch;
            }
            /* Decode byte b as UTF-8, sumb collects incomplete chars */
            if ((b & 0xc0) == 0x80) {            // 10xxxxxx (continuation byte)
                sumb = (sumb << 6) | (b & 0x3f);    // Add 6 bits to sumb
                if (--more == 0) sbuf.append((char) sumb); // Add char to sbuf
            } else if ((b & 0x80) == 0x00) {        // 0xxxxxxx (yields 7 bits)
                sbuf.append((char) b);            // Store in sbuf
            } else if ((b & 0xe0) == 0xc0) {        // 110xxxxx (yields 5 bits)
                sumb = b & 0x1f;
                more = 1;                // Expect 1 more byte
            } else if ((b & 0xf0) == 0xe0) {        // 1110xxxx (yields 4 bits)
                sumb = b & 0x0f;
                more = 2;                // Expect 2 more bytes
            } else if ((b & 0xf8) == 0xf0) {        // 11110xxx (yields 3 bits)
                sumb = b & 0x07;
                more = 3;                // Expect 3 more bytes
            } else if ((b & 0xfc) == 0xf8) {        // 111110xx (yields 2 bits)
                sumb = b & 0x03;
                more = 4;                // Expect 4 more bytes
            } else /*if ((b & 0xfe) == 0xfc)*/ {    // 1111110x (yields 1 bit)
                sumb = b & 0x01;
                more = 5;                // Expect 5 more bytes
            }
            /* We don't test if the UTF-8 encoding is well-formed */
        }
        return sbuf.toString();
    }

    private static final String[] URL_SCHEMA = {
            "http://",
            "https://"
    };

    public static String encodeURL(String url) {
        url = StringUtil.trimToEmpty(url);
        for (String schema : URL_SCHEMA) {
            if (url.startsWith(schema)) {
                return schema + encode(url.substring(schema.length()));
            }
        }
        return encode(url);
    }
}